From: Madalin-Cristian Bucur <madalin.bu...@nxp.com> Date: Mon, 7 Nov 2016 16:32:16 +0000
>> -----Original Message----- >> From: David Miller [mailto:da...@davemloft.net] >> Sent: Monday, November 07, 2016 5:55 PM >> >> From: Madalin-Cristian Bucur <madalin.bu...@nxp.com> >> Date: Mon, 7 Nov 2016 15:43:26 +0000 >> >> >> From: David Miller [mailto:da...@davemloft.net] >> >> Sent: Thursday, November 03, 2016 9:58 PM >> >> >> >> Why? By clearing this, you disallow an important fundamental way to do >> >> performane testing, via pktgen. >> > >> > The Tx path in DPAA requires one to insert a back-pointer to the skb >> into >> > the Tx buffer. On the Tx confirmation path the back-pointer in the >> buffer >> > is used to release the skb. If Tx buffer is shared we'd alter the back- >> pointer >> > and leak/double free skbs. See also >> >> Then have your software state store an array of SKB pointers, one for each >> TX ring entry, just like every other driver does. > > There is no Tx ring in DPAA. Frames are send out on QMan HW queues towards > the FMan for Tx and then received back on Tx confirmation queues for cleanup. > Array traversal would for sure cost more than using the back-pointer. Also, > we can now process confirmations on a different core than the one doing Tx, > we'd have to keep the arrays percpu and force the Tx conf on the same core. > Or add locks. Report back an integer index, like every scsi driver out there which completes tagged queued block I/O operations asynchronously. You can associate the array with a specific TX confirmation queue.
